Objectives: In our work on the design of electrode systems for chronic cerebellar stimulation we have identified a gap in the present state of the art. No technique exists for quantitatively predicting the current pathways through inhomogeneous anisotropic tissue when electrodes are applied. We have been seeking a solution to this problem as a means of improving electrode design. Our present approach employs a two-dimensional model of a mid-saggital section of the human head. A 500-element mesh represents the structural and impedance properties in this mid-saggital section. To be truly representative, this model needs to be upgraded to three dimensions, and to utilize isoparametric elements representing the intracranial structures. Provision for anisotropic resistivity will be included. Methods: A three-dimensional finite element solution routine employing parabolic isoparametric elements will be developed and validated. A structural input file, based on CT images of a normal head, will be created to serve as the boundaries of the finite elements. A separate file of anisotropic resistivity data for each element containing myelinated tracts will also be computed. The model will be tested for sensitivity to errors in the resistivity file using a worst-case analysis. Solution of the equations generated by the model will yield current density and isopotential contours out to the scalp surface. The model predictions will be compared to our database of scalp recordings of stimulus artifact pulses caused by implanted electrodes. Novel electrode designs for cerebellar and deep brain stimulation will be tested for effectiveness using the model.